Owing to the financial effect of the coronavirus pandemic, the Spanish champions are desperate to offload Coutinho this summer to free up space on the wage bill, but they have failed to find a suitor for the Brazilian.
Bayern Munich, who signed Coutinho on loan last summer, has turned down the possibility of a permanent contract through ties to the likes of Chelsea, Everton, Newcastle United, Manchester United and even the Liverpool club have so far come to nothing.
Despite publicly criticizing him earlier this season, Mourinho has refuted rumours of a split with Ndombele, but there have been suggestions that the Spurs record signing has told the manager he never wants to play for him again.
Barcelona, who had been linked to Ndombele before joining Spurs, rekindled their interest but would only be willing and able to make a swap offer, with Coutinho going in the opposite direction as their preferred option.
Ndombele made 27 appearances this season for Tottenham but he only played 12 games in the Premier League.